Photographic silver halide emulsion supersensitized with a c-acyloxy quinoline base



' 1948- B. H. CARROLL ET AL I 2,450,748

' PHOTOGRAPHIC SILVER HALIDE EMULSION SUPERSENSITIZED WITH A C-AGYLOXY QUINOLINE -BASE Filed April 20, 1946 I ,4 3,3- d/eI/gy1-9- mthylselenacarbocyanfne bromide 5 3, .3 diZhyl-9 -mezhylselenacarbo q'anine bmmide plus 6 acezoxyqulholine Patented Oct. 5, 1948 PHOTOGRAPHIC SILV SUPERSENSITIZED QUINOLINE BASE ER HALIDE EMULSION WITH A C-ACYLOXY Burt H. Carroll and John Spence, Rochester,

N. Y., assignor's to Eastman Kodak Company,

Rochester, N. Y;, acorporation of New Jersey Application April 20, 1946, Serial No. 663,762

9 Claims.

This invention relates to sensitized photographic emulsions and to a process for preparing the same. This application is a continuation-inpart of our copendi ng application Serial No. 466,796, filed November 24, 1942 (now United States Patent 2,398,778, dated April 23, 1946).

It is known that the distribution of spectral sensitivity of certain spectr'ally sensitized emulsions can be altered and an increase of sensitivity obtained in some spectral region by incorporating certain additional sensitizing dyes in the spec-- trally sensitized emulsions (see United I States Patent 2,158,882, dated May 16, 1939, and 2,159,565, dated May 23, 1939). The effect thus produced has come to be known as supersensitization. Supersensitization of certain spectrally sensitized emulsions can also be effected by incorporating certain substantially colorless heterocyclic bases, viz. those containing an amino group, in

the spectrally sensitized emulsions. (See United States Patent 2,177,635, dated October 31, 1939.) Supersensitization differs from hypersensitization which involves treatment of finished films or plates, an operation which normally reduces the pAg and increases the pH of the emulsion, with consequent decreased stability.

We have now found a new method for super- ,sensitizing spectrally sensitized emulsions, which not only does not reduce the stability of the emulsions, but is especially valuable as a means of giving good panchromatic sensitized emulsions of high speed and good color balance.

It is,'accordingly, an object of our invention to provide new supersensitized photographic emulsions. A further object isto provide a process for preparing such emulsions. Other objects will become apparent hereinafter.

In accordance with the invention, a photographic silver halide emulsion other than a chloride emulsion, e. g. silver chlorobromide (which may contain small amounts of silver iodide), silver bromide or silver trally sensitized with a (at least one) cyanine dye is supersensitized by incorporating in the emulsion a (at least one) quinoline base containing an (at least one) acyloxy (acyloxyl) group attached to a (at least one) carbon atom of the quinoline base. Our invention is directed principally to emulsions of such grain size that the bromiodide emulsions, spec- I 2 emulsions give a substantially neutral-toned image in Eastman Kodak Company's D76 developer, and should not be confused with prior proposals to obtain blue-black tones in fine-grain emulsions by means of heterocyclic nitrogen bases. Moreover, our invention involves incorporation of the quinoline bases in the emulsion before exposure of the emulsion and should not be confused with proposals to develop with colorforming developers silver salt images, in the presence of certain heterocyclic nitrogen bases which contain a reactive methyl group.

The quinoline bases employed in practicing our invention are quinoline bases containing an acyloxyl group attached to a carbon atom of the quinoline base. Advantageously the acyloxy group is an acetoxy group or a benzoxy group. Examples of the acyloxyquinolines include 6- acetoxyquinoline, 2-acetoxyquinoline, fi-benzoxyquinoline, etc. v

The majority of cyanine dyes which are super.- sensitized by the quinoline bases are characterized by the fact that the dyes produce two types of sensitization depending upon conditions. Such different types of sensitization are described by Leermakers, Carroll and Stand, J. Chem. Physics 5, 878 (1937) and by Schwarz, Sci. et Ind. Phot. 10, 233 (1939). When a cyanine dye of this type is used as a sensitizer in low concentration, it e?!- hibits a sensitizing maximum displaced about20 to m toward the red from the absorption maximum in ethyl alcohol solution. On increasing the concentration of the'dye, or upon digesting the emulsion containing the dye inthe lower concentration, or both, a second maximum of The increase in sensitivity apparently from the same appears to correspond to a more complete conversion than has ever been obtained without a supersensitizer, and in any case the long wavelength sensitivity is better than can be obtained concentration of dye without the quinoline base.

The following are exemplary of the cyanine dyes which are supersensitized in accordance with our invention:

9-ethyl;3,3' dimethylthiacarbqcyanine bromide 5'-chloro-3,3,9-triethylthiacarbocyanine iodide 5,5-dichloro-3,3',9-triethylthiacarbocyanine i0,-

dide 3,3'- diethyl-9-methy1-4,5,'l',5 -dibenzothiacarbocyanine bromide 3.3-diethyl-9-methylselenathiacarbocyanine bromide 5' ch1oro-3,3'-diethyl-9-methylselenathiacarhor cyanine iodide 3,3-diethyl-9-methylselenacarbocyaninebromide 1'-ethyl-3,6-dimethyl-4-phenylthiazolo-2' cya-' nine bromide 3,1-diethyl-6'-methoxythia-2-cyanine bromide 1.. .-':s sthrkzl uaniusbmmi h 1.-.2 .-Qa ya. Premis fisthvl h "flime vlth efl sar an e iodide d ethvl-9me h lph nd x thiasa b n i did I as ed ethyloxa rissrboa nin iod d he sen itizin dyes e m loyed in any desired cqnqen ration- Qrdi a i v f om 0 t 3 msof e e pe liter o emulsion wi l ufiice inv prod ce th pt mum sen itizing e ct Th methods o incorporat n sensi iz ng dyes n emulsionsar Well, kno n t t ose k lle n the ar ordinar it s pretere le o diss ve th are in wa erwmis ib e solvent suobas sthanm metha ol. before n orporat in the emu sio Qne o mo e sens tiz n yes can be em lo edhesam unt om 'noline b em ed is no critical. Usually the full su flrs .nsitizing efi c is developed at a concentration of 0.19 to -1 5, grams per liter of emul on. At thes concentratio practically-non o th uinoline a es has, a

a reci bl ue ton he pHof the emulsion. h siuin line bases can be added to he emulsions w th. b for or after thesens tiz n dy or dyes.

More than on uino ine bas can b employed. Th euinoliu bases are nreterably. but ot nec ssan y. dilu ed with a water-miscibl s lvent. su h as m than l, before inaorn ration in t e mulsi nshe sensit insdye. or dy sanrd the u ncl ne as or ba es ca be add d o th em lu ns at an n i t st e f their pr parat n but p efer bly t -the washed, fore coating.

The following example-will serve to illustrate f t suits obtained in accordance with finished emuls ons b Example sensitized emulsion without the fieacetoiryquinoe 2 a erta con a n n it w ase ueueh es! (Wet r; o, 25, and m n s b u 4 (Wratten N0. 12) filters. The results are tabulated below:

Red Minus Blue fi-acetoxyquinoline (cc. per

liter of emulsion) Speed Gamma Speed Gamma Similarly 6-benzoxyquinoline and other quinoline bases containing an acyloxy group supersensitize the emulsions spectrally sensitized with cyanine dyes. Some of the quinoline bases while efiecting an increase of sensitivity (speed) in some spectral region, cause a decrease in others, and must be employed with that fact in mind.

The accompanying drawing illustrates graphically the supersensitizing effect obtained with one of our new combinations in a gelatino-silverbromoiodide emulsion, The figure is a diagrammatic reproduction of two spectrograms. Curve A represents the sensitivity of the emulsion sensit i z e d with 3,3-diethy1 9 methylselenacarbocyin a concentration of 20 mg. per liter of emulsion. Curve 3 represents the sensitivity of the same emulsion sensitized'with 3,3- diethyl-9-methylselenacarbocyanine bromide in a concentration of 20 mg. per liter of emulsion, G-acetoxyquinoline having also been added to the emulsion in a concentration of 0.25 cc. per liter of emulsion. The supersensitizing or synergistic eiTect of the combination is apparent. G-Acetoxyquinoline, alone, imparts no additional spectral sensitivity to the emulsion.

Our invention is primarily directed to the customarily employed gelatino-silver-halide developing-out emulsions, such as gelatino-silver-chlorobromide, gelatino-silver-bromide and gelatino silver-bromiodide developing-out emulsions, esfor development to black-andwhite images by means of non-color-formin developers, e, g. hydroquinone-N-methyl-p-aminophenol developers.

Emulsions prepared in accordance with our invention can be coated in th usual manner upon any desired support, such as cellulose nitrate support, cellulose acetate support, polyvinyl aoetal resin support, metal support, glass support or paper support.

What we claim'as our invention and desire to be secured by Letters Patent of the United States is:

l. A photographic silver halide emulsion selectedfrom the group consisting of silver chlorobromide, silver bromide and silver bromiodide emulsions spectrally sensitized with a sensitizing cyanine dye containing, as a supersensitizer, a u n i e ba QI BI an acyloxy o p r tached to a carbon atom of the quinoline base.

2- A ph tos oh s ilve ha d d e op n -ou emulsion selected from the group consisting of silver chlorobro nide, silver bromide and silver roiniodide developingrout erni lsions spectrally en it ed wit sensi iz n va e dy co ainn ss upe n it zs z a quin l ne ba contai ing an asv oxv e o pa' ac o a a bon tom of the quino ne bas .3. A photographic ee1atin0-silver-.halidc developing-out emulsion-selected from the group consisting of;gelatino-si1venchlorobromide, gelatino-silveltrbromide and gelatinoesilver-bromioglide developing-out; emulsions spectrally sensitiz s w hensit zin c n dye on ainin as a supersensitizer, a quinoline base containin an acyloxy group attached to a carbon atom of the quinoline base.

4. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a sensitizing cyanine dye and containing, as a supersensitizer, a quinoline base containing an acyloxy group attached to a carbon atom of the quinoline base.

5. A photographic gelatino-silver-halide developing-out emulsion selected from the group consisting of gelatino-silver-chlorobromide, gelatino-silver-bromide and gelatino-silver-bromiodide developing-out emulsions spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum, said emulsion containing as a supersensitizer, a quinoline base containing an acyloxy group attached to a carbon atom of the quinoline base.

6. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum, said emulsion containing, as a supersensitizer, a quinoline base containing an acetoxy group attached to a carbon atom of the quinoline base.

'7. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum, said emulsion containing, as a supersensitizer, 6-acetoxyquinoline.

8. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one con centration and at a higher concentration, or upon digestion of the emulsion at the lower concentration, produces a second maximum of spectral sensitivity at. a wavelength longer than that of the first maximum, said emulsion containing, as a supersensitizer, a quinoline base containing a benzoxy group attached to a carbon atom of the quinoline base.

9. A photographic gelatino-silver-bromiodide developing-out emulsion spectrally sensitized with a cyanine dye which produces a maximum of spectral sensitivity in the emulsion at one concentration and at a higher concentration, or upon digestion of the emulsion at the lower concentration, produces a second maximum of spectral sensitivity at a wavelength longer than that of the first maximum, said emulsion containing, as a supersensitizer, G-benzoxyquinoline.

BURT H. CARROLL. JOHN SPENCE.

REFERENCES CITED UNITED STATES PATENTS Name Date Mees May 16, 1939 Number 

